Musnad Abu Ya'la al-Mawsili 118:27

Zakariya ibn Yahya al-Wasiti narrated to us, Hushaym narrated to us, from Sufyan ibn Husayn, from al-Zuhri, from Anas ibn Malik: That the Prophet (peace be upon him) was brought milk, and he drank. He said: Abu Bakr was on his left, and a Bedouin was on his right. Umar said: "O Messenger of Allah, give it to Abu Bakr." He said: So he gave it to the Bedouin.